#include<stdio.h> #include<string.h> #include<stdlib.h> struct student{ char number[10]; char name[15]; double cscore; double mathscore; double englishscore; double sum; struct student *next; }; void tianjiaxinxi() { int n; FILE *fp; if((fp=fopen("data.txt","w"))==NULL) { printf("File open error!\n") ; exit(0); } printf("请选择添加几名学生的信息：\n");scanf("%d",n); getchar(); struct student u[n]; for(int i=0;i<n;i++) { printf("请输入学生信息：\n"); scanf("%s%s%lf%lf%lf",u[i].number,u[i].name,&u[i].cscore,&u[i].mathscore,&u[i].englishscore); u[i].sum=u[i].cscore+u[i].englishscore+u[i].mathscore; fprintf(fp,"%s %s %.2f %.2f %.2f %.2f", u[i].number,u[i].number,u[i].name,u[i].cscore,u[i].mathscore,u[i].englishscore); } if(fclose(fp)) { printf("Can not close the file!\n"); exit(0); } } int main() { tianjiaxinxi(); return 0; }为什么执行完给n赋值后，按回车就结束程序了

在代码中，scanf的语句`scanf("%d",n);`应该改为`scanf("%d",&n);`，因为scanf需要传入参数的地址，而不是参数本身。所以导致程序在scanf语句处出现了错误。修改后的代码如下：

#include<stdio.h> 
#include<string.h> 
#include<stdlib.h> 

struct student{    
    char number[10];    
    char name[15];    
    double cscore;    
    double mathscore;    
    double englishscore;    
    double sum;    
    struct student *next; 
}; 

void tianjiaxinxi() {    
    int n;    
    FILE *fp;    
    if((fp=fopen("data.txt","w"))==NULL) {        
        printf("File open error!\n") ;        
        exit(0);    
    }    
    printf("请选择添加几名学生的信息：\n");    
    scanf("%d",&n); //修改这里    
    getchar();    
    struct student u[n];    
    for(int i=0;i<n;i++) {        
        printf("请输入学生信息：\n");        
        scanf("%s%s%lf%lf%lf",u[i].number,u[i].name,&u[i].cscore,&u[i].mathscore,&u[i].englishscore);        
        u[i].sum=u[i].cscore+u[i].englishscore+u[i].mathscore;        
        fprintf(fp,"%s %s %.2f %.2f %.2f %.2f", u[i].number,u[i].name,u[i].cscore,u[i].mathscore,u[i].englishscore,u[i].sum);     
    }     
    if(fclose(fp)) {        
        printf("Can not close the file!\n");        
        exit(0);        
    }    
} 

int main() {    
    tianjiaxinxi();    
    return 0; 
}

这样修改后，程序就可以正常运行了。